In the past several years, various printing technologies have been developed which inherently contain the ability to place a dot or picture element (pel) at any point on a page. For example, laser electrophotographic printers such as the IBM 3800 and the IBM 6670 have that capability. Other types of electrophotographic printers such as light emitting diode (LED) also have that capability. Additionally, magnetic printers, ion deposition printers, and dot matrix printers can all have an all points printable capability.
An all points addressable (APA) printer is a printer such as described above which can be commanded to print a dot or picture element at any point on a page. An APA printer, therefore, is a printer which is not only capable of printing at any coordinate position but is one that contains a control unit enabling it to be commanded to do that. For example, the IBM 6670 laser printer, mentioned above, is not an APA printer although the technology of the print engine inherently had that capability. In recent years, several printers have been developed with an APA capability including the IBM 3800 Model 3.
Despite the development of APA printers, software support for advanced function printing utilizing such printers has lagged far behind the development of the print engines themselves. As a result, the inherent capabilities of the APA printers to handle various typographic fonts and to present composed pages containing a mixture of text, image, and graphics data have not been fully exploited in data processing and office systems. By graphics data is meant line drawings whereas image data is exampled by photographs.
The lack of software support for advanced function printing, however, is in large measure, attributable to the large number of new and different all points addressable printers each of which has its own unique data processing process that frequently bears little resemblance from one machine to another for an equivalent function. Furthermore, many of these processes have printing functions so primitive that a considerable amount of effort is required by the using software to prepare data for the printer.
Another factor which has inhibited the growth of host application programs utilizing APA printers has been the complexity of managing auxiliary resources such as various font patterns and electronic form descriptions that must be downloaded to the printer prior to the printing of pages. Typically, the prior art has required the host application to prepare a bit map of the information to be printed and to transmit that map bit by bit to the printer. The IBM 3800 Model 3, an APA Printer, has improved on that type of data transmission but is limited to data transmission over data channels. As a result, host application software utilizing the model 3 is usable only with the model 3 or another channel attached printer.
One major object which this invention achieves is to enable the transmission of data to be printed from a host application to an APA printer over any type of communicating medium; channel, telecommunication lines, local area network, microwave, etc. and to transmit that data and utilize the full functional capability of an APA printer without regard to the type of transmission protocol in use. Furthermore, the process of this invention attains the object of making the host application software completely independent of the type of printing technology used at the APA printer. That is, the printer can utilize any type of printing technology and it can have any type of microprocessor associated with the printer control unit processing the commands and data received through use of the inventive process. Moreover, the process enables the transmission of any kind of data type, that is, textual data, image data, graphics data, or bar code data. Additionally, the process enables these different data types to be mixed together for presentation on a single page.
As a result of the use of the process of this invention, designers of APA printers are free to pursue any type of technology and be assured of a large well-developed range of application host software available to use the product when it becomes available.
Additionally, use of the process of this invention enables software designers to develop better and better software for utilizing the capabilities of APA printers without fear of their products becoming obsolete because they are tied to a particular printer or a particular print technology. Use of the process of this invention makes the software usable with any APA printer and moreover, makes it usable over any type of communicating medium.